Khloe KardashianKris Humphries Is SICK ...Mom Didn't Stage Sex Tape

6/21/2012 1:24 PM PDT

Kris Humphries invented the story about Kris Jennermasterminding Kim Kardashian's sex tape in order to live out a "disgusting" fantasy -- this according to Kim's sister Khloe Kardashian.

Khloe was out in New York today when we asked her about the TMZ story -- that Humphries told his ex-girlfriend that Kris Jenner directed Kim to make her infamous sex tape ... and even had Kim re-shoot it because the first take wasn't pretty enough.

Khloe responded, "That is just disgusting and disturbing, and probably HIS fantasy!"

It's a shocking statement coming from the woman who defended Humphries just days ago -- calling him "a good guy" unfairly caught up in a cruel extortion plot.